Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753995AbbEAP23 (ORCPT ); Fri, 1 May 2015 11:28:29 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:54084 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753625AbbEAP22 (ORCPT ); Fri, 1 May 2015 11:28:28 -0400 From: Davidlohr Bueso To: Peter Zijlstra , Thomas Gleixner , Ingo Molnar Cc: Sebastian Andrzej Siewior , Linus Torvalds , Chris Mason , Steven Rostedt , Manfred Spraul , George Spelvin , linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: [PATCH v2 0/3] kernel: lockless wake-queues Date: Fri, 1 May 2015 08:27:49 -0700 Message-Id: <1430494072-30283-1-git-send-email-dave@stgolabs.net> X-Mailer: git-send-email 2.1.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1959 Lines: 47 Hello, This series is aimed at addressing some of the futex hash bucket lock hold times by introducing lockless wake-queues for futex_wake. patch-1: introduces the lockless wake-queue machinery. patch-2: makes use of patch 1 for futexes. patch-3: makes use of patch 1 for posix mqueues. Details in the individual patches. This was suggested sometime ago by peterz, but due to it potentially causing spurious wakeups, was never given much consideration. However, nowadays, so far, I am reliably booting a 45-core box with peterz's patch to trigger spurious wakeups. While there are drivers out there that do not play nice with schedule(), they can be fixed over time -- while this is a production problem for some customers). Furthermore, after some auditing, there really aren't that many, it a lot of cases, those functions that end up calling schedule are merely wrapped in a loop, so just not clear at first sight. Changes from v1: - Simplify wake_q and more comments, suggested by George Spelvin. - Made it very clear in the comments that this can cause spurious wakeups, and how naughty users should handle them. (Linus) - Added mqueue user as this was also wanted for rt purposes. Applies on top of Linus' tree 4.0-rc1 (4a152c3913f). Thanks! sched: lockless wake-queues futex: lockless wakeups ipc/mqueue: lockless pipelined wakeups include/linux/sched.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++ ipc/mqueue.c | 50 +++++++++++++++++++++++++++++++------------------- kernel/futex.c | 33 +++++++++++++++++---------------- kernel/sched/core.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 140 insertions(+), 35 deletions(-) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/